JPS58220908A - Energy damper structure for turbine by-pass steam - Google Patents

Abstract

PURPOSE:To reduce breakage of the cooling pipes of a condenser and improve the safety of a plant by forming a plurality of injection holes in zigzag form on the pipe wall opposed to an energy damper pipe, thus permitting the steam energy to be dissipated and uniformalizing the temperature and the flow speed. CONSTITUTION:Injection holes are formed in zigzag form and the jet-flow zone a-b-b'-a' of jet flow from an injection hole 45b is separated from the jet-flow zone c-d-d'-c' of jet flow from an injection hole 46b opposed to the injection hole 45b, and generation of the shock wave caused by the collision of the ultrasonic jet-flow which is jetted from each injection hole is reduced, and the field of steam in the space surrounded by energy amper pipes 31a and 31b is stabilized. Further, in the space surrounded by the jet-flow zones a-b-b'-c', the boundary b-b' and the bounary c-c' each of which having a small speed are set close to each other, a mixed range in which eddy current is generated is formed, and the energy at a high level which is jetted from the pipes 31a and 31b is effectively dissipated and damped with eddy current.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to the structural pressure of a turbine bypass steam energy damper in a steam motor plant.

Modern large-capacity steam power plants are equipped with a turbine bypass system that directly introduces the main steam of the turbine into the condenser in order to shorten the turbine startup time and ensure smooth startup, as well as to ensure the safety of component equipment. are doing.

FIG. 1 is a steam system diagram showing an example of a steam motor plant for nuclear power generation equipped with a turbine bypass system.

1 is a nuclear reactor that is a high-temperature, high-pressure steam source; 4 is a high-pressure turbine;
6 and 7 are brackish water separation and reheaters, 1o is a low pressure: 1 bottle, 11 is a condenser, 14 is a low pressure feed water heater, and 16 is a high pressure feed water heater.

The turbine bypass system is configured by connecting a bypass pipe 18, which is obtained by branching the upstream pipe 2 of the main steam blocking valve 3 of the high-pressure turbine 4, to the condenser 11. A pressure reducing valve 19 is interposed and connected in the middle of the bypass pipe 18, and an energy damper 20 is provided at the connection part with the condenser 11 to expand and reduce the pressure of the bypass steam to the internal pressure of the condenser.

FIG. 2 is a cross-sectional view showing a conventionally commonly used energy damper structure.

A tube nest 34a consisting of a group of cooling tubes is provided in the condenser 11.

34b and 34C are provided, and energy dampers 20 are provided on both sides thereof.

The energy damper 2o is located on the steam inflow side (left side in the figure) of a steam pipe 6o connected to the turbine bypass steam pipe 22.
A conical perforated plate 23 is provided on the steam outflow side (right side in the figure).
A conical perforated plate 24 and a circular perforated plate 25 are installed on the side wall near the steam inlet side, and a detemperature water injection device is installed on the side wall near the steam inflow side. 1lV21 is provided.

1:1: The steam expansion process when turbine bypass steam is introduced into the condenser 11 through the energy damper 2° configured as above is summarized below using the enthalpy-entropy diagram in FIG. Describe.

Pressure P. The steam (0) is reduced to a pressure P by the pressure reduction control valve 19 (state 1), and further expanded to a critical pressure by the conical perforated plate 23 (state 1''), and the pressure in the mixing chamber 61 in the steam pipe 60 is P. Expand and depressurize until !Condition 1''~2'
), the temperature is reduced from state 2' to state 2 by injecting detemperature water. Also, the steam in state 2 expands and depressurizes in the critical pressure trench by the perforated plate 24, and from state 2, the condenser internal pressure P decreases.
It is further expanded and depressurized to c and becomes steam in state 3, completing the expansion process.

The energy damper 20 of the conventional structure shown in FIG. In order to expand the steam, the steam ejected into the condenser 11 tends to be insufficiently diffused. For this reason, the cooling pipe nest 3 installed below the energy damper 20
It is difficult to uniformly distribute steam to 4a, 34b, and 34C, and locally high-velocity steam flows into tube nest 3.
4a, 34b, or 34C, which may cause damage to the cooling pipe. Further, the perforated plate 23 provided in the steam pipe 60. 25 is not necessarily sufficient in terms of reliability, such as strength and vibration.

The present invention was made in view of the above-mentioned circumstances, and diffuses the energy of the steam ejected into the condenser to equalize its temperature φ pressure and flow velocity, thereby reducing damage to the condenser cooling pipe and plant component equipment. The purpose is to contribute to improving safety and reliability.

The present invention provides that a supersonic jet flow state occurs in the process of introducing turbine bypass steam into a condenser to expand and decompress it, and that the length of this supersonic jet is related to the Matscha number of the jetted steam. Taking advantage of the fact that if steam is ejected from injection holes that are placed opposite each other at intervals longer than the jet length mentioned above, the flow instability phenomenon caused by supersonic jets will be reduced. , the injection holes installed opposite each other are arranged in a staggered manner to avoid direct collision of the steam jets, and the energy of the ejected steam is diffused by using the vortex of the mixing region formed at the interface between the jets.・It is designed to attenuate it.

In order to achieve the above object by applying the above principle, the present invention provides a plurality of tubular members for energy dampers (hereinafter abbreviated as energy damper pipes) installed parallel to the axis of a condenser cooling pipe. and the energy damper tubes each have a plurality of injection holes in their opposing tube walls,
The present invention is characterized in that the nine injection holes, which are opposed to each other, are arranged in a staggered manner.

Next, an embodiment of the present invention will be described with reference to FIGS. 4 to 13.

FIG. 4 is a cross-sectional front view of a condenser equipped with an embodiment of the turbine bypass steam energy damper structure according to the present invention;
FIG. 5 is a sectional side view of the same.

The main body of the condenser 11 is connected to the lower part of the casing 26 of the low-pressure turbine via a condenser connection shell 29.
7d1 and 28a to 28d are led, and the above-mentioned extraction steam pipes 278 to 27d are connected to low pressure feed water heaters 30a and 30b.

By applying the present invention to the condenser configured as described above, an energy damper pipe 31a is constructed which constitutes an energy damper above the cooling pipe bundles 34a and 34b, in parallel with the pipe axes thereof.
, 31b will be installed.

The cooling pipe group of a condenser is often installed divided into two tube bundles, and the condenser 11 in which the present embodiment is arranged in a row also includes two tube bundles 34a and 34b.

In this embodiment, there are two tubes 31a for kneading.

31b is installed.

FIG. 6 is an enlarged cross-sectional side view showing the cooling pipe nests 34a, 34b and the energy damper pipes 31a, 31b.
FIG. 7 shows the energy pipes 31a and 31b'
It is a plan view extracted and drawn.

As shown in Figure 6, two energy dunnoku '13
The injection holes 40b are formed in the pipe wall of the example in which the pipes 1a and 31b face each other, each facing toward the other damper pipe.

41a, ' In this embodiment, two energy damper pipes 31a, 3
1b has an extra space with the condenser connection body 29, so the above-mentioned injection hole 4 is installed in the pipe wall of the energy damper pipe 31a.
To the injection hole 408 in the exact opposite direction of 0b? Similarly, an injection hole 41b is bored in the wall of the energy damper pipe 31b. As shown in FIG. 7, there are two energy protein tubes 31a.

3], b are arranged at intervals of 2L. This dimension will be described later with reference to FIG.

A plurality of the injection holes 40a, 40b, 41a, 41b are arranged in a row in the longitudinal direction of the energy damper pipes 31a, 31b, respectively, on the side walls of the energy damper pipes 31a, 31b.

The steam ejected from these injection holes is a steam jet 36a,
36b, 37a, and 37b, which are ejected into the condenser, diffused, and depressurized while cooling pipe nest 34a.

Steam flows 38a-38d and 39a-3 toward 34b
9d, which contacts the outer peripheral surfaces of the tube nests 34a and 34b and condenses through heat exchange.

FIG. 8 shows the two energy damper pipes 31a.

31b and a condenser side wall 42, 43 are explanatory diagrams showing the mutual spacing. FIG.

As explained with reference to FIG. 1, the turbine bypass steam is branched from the turbine main steam and guided to the energy damper pipes 31a, 31b while being expanded and reduced in several stages by the pressure reduction control valve 19 or the pressure reduction orifice (not shown).

The steam pressure when reaching the condenser is usually 5~l Q k
g/cm', and this steam is heated to a vacuum degree of 720 mmH.
If the steam is directly injected into the condenser around g, the steam flow rate will be about 3 to 4. Matsuno and Kazu M in this case
J is determined by the following formula.

MJ = ((Pa/P,)cr-1)/r-13
-1 And the length Ls of the section where the steam jet flows at supersonic speed is M
As a function of J, as shown in Figure 9, −Ls and M
It is proportional to J.

The damper pipes 31a, 31b shown in FIG. 7 are provided with injection holes 40b, 41a so as to face each other directly, but when the ejected steam flows collide head-on in this way, the distance between both injection holes is sufficient. However, if the interval 2L is less than twice the length Lm of the supersonic flow, there is a risk that the supersonic jets will collide with each other and generate shock waves, resulting in an unstable flow state. be.

As a result of research on the above unstable flow phenomenon, the inventors found that L
It was experimentally confirmed that if the condition of >1.8LB DJ is satisfied, the occurrence of unstable flow phenomenon can be avoided.

If L<1.8L8DJ, there is a possibility that an unstable flow phenomenon will occur. Also, L)) 1.8Ls DJIC more than necessary
This increases the size of the condenser body, which is uneconomical.

Therefore, considering an appropriate safety factor, L is set as L>1.8LsDJ, and as shown in FIG. It is desirable to set it to L.

If it is not possible to take the above interval, the i o,′
As shown in the figure, the tube spacing is set to 2L, and the injection holes (40a, 41b in FIG. 8) facing the side wall are omitted, or the injection hole diameter DJ is made small so that the above-mentioned conditional expression L>1.
8LsLJJ must be satisfied, but the present invention provides a configuration that can avoid the unstable flow phenomenon without reducing the injection hole diameter DJ as described below. FIG. 11 shows a configuration for avoiding the above unstable flow phenomenon.

In the examples shown in FIGS. 8 and 10, the interval between the pipes had to be 2L, but in the embodiment shown in FIG.

An injection hole is provided in 31b as follows. That is, the injection hole 46a is bored in the energy damper pipe 31a.

46b... and injection holes 45a, 45b... bored in the energy damper pipe 31b are arranged in a staggered manner.

The injection holes 46a, 46b, and 45a are explained in detail as follows.

Assuming an axial reference line S as appropriate, this reference line S force is 60
JtJMJL46a,'4'5a,46btfo
Let lffiMe be X, ,X, ,X, respectively. Then, the values of X, , X, and X are set so that the relationship Xt = (X+ +Xs)/2 is established.

Similarly, regarding the injection holes 45a, 46b, 45b,
” (X 2 +

When the injection holes are arranged in this way, for example, the jet from the injection hole 45b has a jet zone formed by (a-b-b'-a), and a jet zone from the opposite injection hole 46b (c-d- d'-c') to reduce the generation of shock waves caused by the collision of supersonic jets ejected from each other's injection holes, thereby stabilizing the flow field in the space surrounded by the energy damper pipes 31a and 31b. let Moreover, the jet zone (a-b-b'-a') and the jet sea y (c-d-
In the space between d'-c'), the velocity is small (
Because the b-b/) boundary and the (c-c') boundary are close,
This becomes a mixing region where a vortex is formed, and the energy damper pipe 31
a.

This has the effect of dissipating and attenuating the high level energy ejected from 31b along with the vortex.

Next, a method for appropriately distributing steam ejected from the energy damper pipe in the axial direction of the cooling pipe bundle located below will be explained with reference to FIG.

The importance of proper distribution of blown steam affects condenser cooling performance and reliability. In other words, not only does the heat load become uneven in the axial direction of the cooling pipe where condensation is going to occur, deteriorating the cooling performance, but also the flow locally collides with the cooling pipe, causing damage to the cooling pipe. There is a fear. In the present invention, the first
As shown in Fig. 2, the injection hole diameters DJ, DJ, ... DJN-1, DJN of the injection holes 45a, 45b, .
Opening area Fbl.

The injection hole arrangement is such that Fbt+...FbN-1, FbN gradually increases toward the outflow end so as to satisfy the following equation.

(Fd/FbN)2(Pd/FbN-+)2==1.6
n+0.5 Here, l'll: Cross-sectional area of the energy damper pipe FbN: Opening area of the Nth injection hole n: Number of injection holes Figure 13 shows the strength of turbulence Y: 7w, and the maximum speed of the jet. shows the relationship between the attenuation start position X/D s.

However, ω: Fluctuation speed of the jet flow (m/S) Wo: Average speed of the jet flow (m/S')
This indicates that the distance 1) from the nozzle hole becomes shorter.

In the embodiments shown in FIGS. 14(a) and 14(b), the inner wall of the energy damper pipe 31 is provided with irregularities in order to promote the turbulence of the jet flow by applying the above-mentioned principle.

In the embodiment shown in FIG. 14(a), thin cylindrical members 50a, 50b, 50C, and 50d, which are parallel to the axis of the tubular member, are fixed near the steam inflow portions of the injection holes 45a and 45b to form the inside of the energy damper pipe 31. This is done by forming depressions on the wall surface.

FIG. 14(b) ty) In the embodiment, the injection holes 45a, 45
A large number of thin cylindrical members 51a and 51b are fixed to the inner wall surface of the energy damper pipe 31 avoiding the steam inflow part b to form unevenness.

FIG. 15 is a diagram illustrating a different embodiment from the above, in which thin cylindrical members 51 are lined up and fixed near the injection holes 458 to 45C on the inner wall surface of the energy damper pipe 31, and serrated unevenness 5
2 and triangular unevenness 53 are formed.

) Saccharide Forming irregularities on the inner wall surface of the energy damper pipe 31 as shown in Fig. 14 (a), (b) or Fig. 15 promotes turbulence in the steam flow, thereby promoting attenuation of the steam jet. The energy of the turbine bypass steam is spread evenly.

Figure 16 (a), (b), (C), (d), (
e) shows the configuration of injection holes in different embodiments.

The embodiment shown in FIG. 16(a) is the injection hole 40a described above.

40b, 41a, or 41b with the steam flow direction and 11! , attaches a vertical mesh member. In the embodiment shown in FIG. 16(b), a plurality of parallel columns are attached in the same manner as above.

In this way, attaching a thin rod-shaped member that intersects with the direction of the steam flow promotes turbulence in the steam flow and promotes damping.
The same effects as the embodiments shown in FIGS. 14(a), 14(b) and 15 cannot be obtained.

In the embodiments shown in FIGS. 16(C), 16(d), and 16(e), irregularities of various shapes are formed on the inner wall surface of the injection hole. When such a configuration is used, the turbulence of the steam flow is promoted, and the same effect as in the above-mentioned embodiment (FIGS. 16(a) and 16(b)) is obtained.

As explained above, the present invention provides a cooling pipe nest in which a turbine bypass steamer of a steam power plant having a steam generator, a high pressure turbine, a low pressure turbine, a condenser, and a turbine bypass system is installed in a condenser. The left energy damper structure introduced in the upper part is composed of a plurality of energy damper pipes installed parallel to the cooling pipe axis, and a plurality of injection holes are provided in the mutually opposing pipe walls of the energy damper pipes, respectively, By arranging the injection holes facing each other in a staggered manner, the energy of the steam ejected into the condenser is diffused to equalize its temperature and flow rate, thereby preventing damage to the condenser cooling pipes. It is possible to improve the safety and reliability of plant component equipment by reducing the

[Brief explanation of the drawing]

Figure 1 is a layout diagram of a steam motor plant that uses nuclear power as a steam source, Figure 2 is a sectional view of a conventional steam energy damper, Figure 3 is an enthalpy-entropy diagram showing the expansion process of bypass steam, and Figure 4 is a cross-sectional front view of a condenser equipped with a bypass steam energy damper structure to which the present invention is applied;
Fig. 5 is a cross-sectional side view of the same, Fig. 6 is a partially enlarged view of Fig. 5, Fig. 7 is a plan view depicting the energy damper pipe shown in Fig. 6, and Fig. 8 is a -F energy damper. An explanatory diagram of the arrangement of the pipes, Fig. 9 is a diagram showing the characteristics of supersonic jet flow, Fig. 10 is an explanatory diagram of the arrangement of the energy damper pipe in an embodiment different from the above, and Fig. 11 is a further different embodiment. FIG. 12 is an explanatory diagram of the selection of the injection hole diameter, FIG. 13 is a diagram showing the relationship between steam flow turbulence and steam jet attenuation, and FIG. 14 (a)
), (b) and FIG. 15 are cross-sectional views of energy tamper tubes in further different embodiments, respectively, and FIG. 16(a) to FIG.
(e) is a front view of injection holes provided in the energy damper pipe in further different embodiments. 18... Bypass pipe, 20... Energy damper,
26...Low pressure turbine casing, 27a to 27d. 288-28d... Bleed steam pipe, 29... Condenser connection shell, 30a, 30b-... Low pressure feed water heater, 31a. 31b...Energy damper pipe, 32.33...Water chamber, 34a, 34b, 34C-...Pipe nest, 36a, 36
b. 37a, 37b, , steam jet, 38a-38d39
a ~39d-...Steam flow, 4tJa, 40b, 45a
, 45b, 46a, 46b...% firing hole, 42°43.
, condenser side wall, soa~5ocl, 51a. 51b...Thin rod-shaped member, 52... Serrated unevenness, 5
3...Triangular unevenness. Perforation 1 Closed ￥3 Figure v'4 Figure 1. Rikan ♀ l Fig. certain 7 m Chio °δ Fig. MJ 1θ Fig. 721] Chicho 73 m Certain 15 Fig. 1 4j 8 Inoushi ♀ l Otsu diagram (cL) \\ ゝ (en (b) (d)

Claims (1)

[Claims] 1. An energy damper for introducing turbine bypass steam of a steam motor plant having a steam generator, a pressure control turbine, a low pressure turbine, a condenser, and a turbine bypass system into the upper part of a condenser cooling pipe network. The structure includes a plurality of energy damper tubular members installed parallel to the cooling pipe axis, and a plurality of injection holes are provided in the mutually opposing pipe walls of the energy damper tubular members, respectively, and the This is an energy damper structure for turbine bypass steam in which the injection holes are arranged in a staggered manner. 2. The cross-sectional area Fh of the injection hole is (Fd/Fb(-++)l" (Fd/Fb+,)2
=1.6n+0.5 where Fd: cross-sectional area of the tubular member n: number of injection holes The turbine bypass steam energy damper structure according to claim 1, wherein the structure has the following relationship. 3. The turbine bypass steam energy damper structure according to claim 1 or 2, wherein the inner wall surface of the energy damper tubular member is provided with irregularities. 4. Claims 1 or 2, characterized in that a thin rod-like member is attached to the upstream end of the injection hole provided in the energy damper tubular member in a direction that intersects with the flow direction of the steam. The turbine bypass steam energy damper structure described in . 5. The turbine bypass steam energy damper structure according to claim 1 or 2, characterized in that the inner wall surface of the injection hole provided in the energy damper tubular member is formed with irregularities. 6. Claim 1, characterized in that the distance between the plurality of energy damper tubular members is not equal to L>1.8L8DJ, where L8: ultrasonic jet length DJ: injection hole diameter The turbine bypass steam energy damper structure described in .